National Repository of Grey Literature 2 records found  Search took 0.01 seconds. 
Modification of murine tumor cell lines with CRISPR/Cas9 system and their characterization
Lhotáková, Karolína ; Poláková, Ingrid (advisor) ; Brábek, Jan (referee)
MHCI molecules are constitutively expressed in all nucleated cells and play a key role in antigen presentation to CD8+ T lymphocytes. One of the tumor immune evasion strategies is MHCI expression downregulation. This leads to an impaired recognition of tumor antigens by CD8+ T lymphocytes that are unable to start the immune response. Since the MHCI expression downregulation occurs in up to 90 % of some tumors it is neccesary to have a clinical relevant tumor model without a MHCI surface expression that would be used for testing of immunotherapeutic approaches. This thesis describes a production of new model cell lines of TC-1 tumor cells with irreversibly downregulated MHCI. That was achieved by an inactivation of B2m, which is a part of MHCI, by gene editing using CRISR/Cas9. The B2m inactivation was confirmed by flow cytometry, western blot and sanger sequencing of single alleles. The inactivation slowed down the cell growth for both in vitro and in vivo. The cell metastatic activity was not affected. The tumors established by cells without the B2m expression are not sensitive to DNA vaccine against HPV16 E7 oncoprotein by a pBSC/PADRE.E7GGG vaccine. The main effector function against these tumors possess the NK1.1+ cells. In a therapeutic vaccination experiment it was repeatedly achieved of...
Significance of MHC class I molecules in antitumor immunity
Lhotáková, Karolína ; Poláková, Ingrid (advisor) ; Horníková, Lenka (referee)
The main function of the major histocompatibility complex class I (MHC I) glycoproteins is to present antigenic peptides to CD8+ T lymphocytes. Majority of the peptides displayed by this complex come from cell protein degradation and CD8+ T lymphocytes do not respond to them. Tumor development leads to alterations in protein production and new epitopes are generated which impacts peptide repertoire presented by MHC I glycoproteins on the cell surface. Peptides originated from tumor antigens activate CD8+ T lymphocytes and induce anti-tumor immune responses. Decreased surface expression of MHC I molecules is a common phenomenon in tumor cells that prevents effective immune response. As appropriate MHC I expression level on tumor cells is needed for their effective killing by T cell-mediated immune response, downregulation of the MHC I expression may lead to the selection of tumor cells with decreased MHC I level. This downregulation can be either reversible or irreversible, affecting not only the expression of genes encoding the light and heavy chains of MHC I molecules, but also genes of the antigen-processing machinery (APM). Immunotherapeutics focused on the induction of surface expression of MHC I molecules often have other unfavorable impacts on the immune system. Therefore, a new approach is...

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